A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section.
A fuel system for a gas turbine engine meters and controls fuel flow to the combustor and other portions of the gas turbine engine that utilizes fuel flow and pressure for operating actuators and other control elements. During startup and shutdown of the gas turbine engine fuel flow and pressure may be below desired levels for operation. It is desirable to prevent fuel flow to the gas turbine engine, actuators and other control elements until such time as required pressure and flow are present. It is therefore desirable to control and prevent fuel flow to the combustor and other elements of the gas turbine engine until such time as the fuel pressure and flow are within a predetermined operating range.